Add comment parsing

lysp/example0.lysp

@@ -1,3 +1,5 @@
+;; vi:ft=lisp:sw=2:ts=2
+
 (defun return-1 () 1)
 (assert (= 1 (return-1)))
 (assert (< 1 2 3 4))
@@ -16,11 +18,26 @@
 (setq a 1)
 (assert (= a 1))
 
-(assert (= 6
-    (let (a 1)
-        (let (b 2)
-            (+ a b 3)
-        )
+
+(assert
+  (=
+    6
+    ;; Non-sequential let: bindings will be visible only inside the block
+    (let
+      (a 1)
+      (let
+        (a 100 b (+ a 2))
+        (+ b 3)
+      )
     )
-))
-(assert (/= (let (a 2) a) a))
+    ;; Sequential let: bindings are visible immediately in the asignments
+    (let
+      (a 100)
+      (let*
+        (a 1 b (+ a 2))
+        (+ b 3)
+      )
+    )
+  )
+)
+

lysp/example1.lysp

@@ -0,0 +1 @@
+;; vi:ft=lisp:sw=2:ts=2

src/compile/block.rs

@@ -21,7 +21,7 @@ pub struct CompiledFunction {
 
 struct LocalScope {
     start_index: u32,
-    locals: Vec<Rc<str>>,
+    locals: Vec<(Rc<str>, bool)>,
 }
 
 pub struct FunctionBlock {
@@ -40,21 +40,26 @@ pub struct LocalBlock<'a> {
 }
 
 impl LocalScope {
-    pub fn get_or_insert(&mut self, value: Rc<str>) -> Result<U<16>, CompileError> {
-        let index = if let Some(index) = self.locals.iter().position(|v| *v == value) {
+    pub fn get_or_insert(&mut self, value: Rc<str>, visible: bool) -> Result<U<16>, CompileError> {
+        let index = if let Some(index) = self.locals.iter().position(|v| v.0 == value) {
+            self.locals[index].1 = visible;
             index
         } else {
             let index = self.locals.len();
-            self.locals.push(value);
+            self.locals.push((value, visible));
             index
         } + self.start_index as usize;
         Ok(U::new(index as u32).unwrap())
     }
 
+    pub fn make_visible(&mut self, index: U<16>) {
+        self.locals[usize::from(index) - self.start_index as usize].1 = true;
+    }
+
     pub fn get(&self, value: &str) -> Option<U<16>> {
         self.locals
             .iter()
-            .position(|v| v.as_ref() == value)
+            .position(|v| v.0.as_ref() == value && v.1)
             .map(|v| v + self.start_index as usize)
             .and_then(|v| U::new(v as u32))
     }
@@ -196,15 +201,16 @@ impl<'a> LocalBlock<'a> {
         &mut self,
         identifier: &Rc<str>,
         value: CompileValue,
-    ) -> Result<(), CompileError> {
+        visible: bool,
+    ) -> Result<U<16>, CompileError> {
         let index = self
             .function
             .local_scope_mut()
             .unwrap()
-            .get_or_insert(identifier.clone())?;
+            .get_or_insert(identifier.clone(), visible)?;
         self.compile_push(value)?;
         self.function.emit(Instruction::SetLocal(index));
-        Ok(())
+        Ok(index)
     }
 
     fn compile_push(&mut self, value: CompileValue) -> Result<(), CompileError> {
@@ -405,9 +411,18 @@ impl<'a> LocalBlock<'a> {
 
     fn compile_let(&mut self, binding: &LetExpression) -> Result<CompileValue, CompileError> {
         self.function.push_local_scope();
+        let mut indices = vec![];
         for pair in &binding.bindings {
             let value = self.compile_expression(&pair.value)?;
-            self.compile_set_local(&pair.identifier, value)?;
+            let index = self.compile_set_local(&pair.identifier, value, binding.sequential)?;
+            indices.push(index);
+        }
+        if !binding.sequential {
+            // Make let bindings visible
+            let scope = self.function.local_scope_mut().unwrap();
+            for index in indices {
+                scope.make_visible(index);
+            }
         }
         for expr in &binding.body.head {
             self.compile_statement(expr)?;

src/main.rs

@@ -12,7 +12,7 @@ use lysp::{
         CompilationModule, CompileError, Expression, FunctionBody, FunctionSignature, ParseError,
     },
     error::EvalError,
-    parse::parse_value,
+    parse::{parse_value, skip_comment_and_whitespace},
     vm::{
         machine::{EvalResult, Machine, MachineError},
         prelude,
@@ -57,6 +57,12 @@ fn run_interactive(vm: &mut Machine) -> Result<(), Error> {
 
         let mut i = input.trim_start();
         while !i.is_empty() {
+            i = match skip_comment_and_whitespace(i) {
+                Ok((i, _)) => i,
+                Err(e) => {
+                    todo!("{e:?}")
+                }
+            };
             let result = parse_value(i);
             let (o, value) = match result {
                 Ok(r) => r,
@@ -148,6 +154,12 @@ fn run_module<P: AsRef<Path>>(vm: &mut Machine, path: P) -> Result<(), Error> {
 
         let mut i = input.trim_start();
         while !i.is_empty() {
+            i = match skip_comment_and_whitespace(i) {
+                Ok((i, _)) => i,
+                Err(e) => {
+                    todo!("{e:?}")
+                }
+            };
             let result = parse_value(i);
             let (o, value) = match result {
                 Ok(r) => r,

src/parse.rs

@@ -1,10 +1,10 @@
 use nom::{
-    FindToken, IResult, Input, Parser,
+    AsChar, FindToken, IResult, Input, Parser,
     branch::alt,
     bytes::streaming::tag,
     character::{
         anychar,
-        streaming::{char, multispace0, one_of},
+        streaming::{char, one_of},
     },
     combinator::{map, map_res, opt, recognize, value},
     error::{Error, ErrorKind, FromExternalError, ParseError},
@@ -169,8 +169,8 @@ fn parse_list_or_nil(input: &str) -> IResult<&str, Value> {
     map(
         delimited(
             char('('),
-            many0(preceded(multispace0, parse_value)),
-            preceded(multispace0, char(')')),
+            many0(preceded(skip_comment_and_whitespace, parse_value)),
+            preceded(skip_comment_and_whitespace, char(')')),
         ),
         Value::list_or_nil,
     )
@@ -190,6 +190,36 @@ fn parse_boolean(input: &str) -> IResult<&str, Value> {
     .parse(input)
 }
 
+pub fn skip_comment_and_whitespace(mut input: &str) -> IResult<&str, ()> {
+    let mut in_comment = false;
+    while let Some(ch) = input.chars().next() {
+        let next = input.ceil_char_boundary(1);
+        if next >= input.len() {
+            break;
+        }
+
+        if ch == ';' {
+            in_comment = true;
+        }
+
+        if in_comment {
+            if ch.is_newline() {
+                in_comment = false;
+            }
+
+            input = &input[next..];
+            continue;
+        } else if ch.is_whitespace() || ch.is_newline() {
+            input = &input[next..];
+            continue;
+        }
+
+        break;
+    }
+    input = input.trim_start();
+    Ok((input, ()))
+}
+
 pub fn parse_value(input: &str) -> IResult<&str, Value> {
     alt((
         parse_list_or_nil,